Pour half of the batter into a greased 8-inch square pan. Sprinkle the top with half of the brown sugar mixture plus half of the chocolate chips. Drizzle the rest of the cake batter over the chocolate chips. Sprinkle the top with the remaining brown sugar mixture, and the rest of the chocolate chips. Bake the cake according to the directions on the package, about 60 minutes, or until a tester inserted into the cake comes out clean (although it may have a little melted chocolate on it). Sometimes I find that I need to bake the coffee cake for an additional 5 minutes or so. That’s it folks! You can also substitute your favorite chopped nuts for the chocolate chips, or add both.